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Trouble free scale bar - scale bar length to remain constant size

February 23 2011 | 5 comments
Categories: Map Elements

At our organization users generally want a scale bar which is constant size and a useful size, like 1" or 2" wide. So that when the map scale changes, the scale bar size remains the same and the division values change. Now the key is to set this up in the temaplate and forget about it. I have seen some responses to this question from ESRI staff which basically say you can do this but you will have to adjust your scale bar properties each time you change the scale. This is not a very useful solution. Why require the cartographer to be constantly vigilant about the scale bar? This should just work automaticlly, in my opinion. In the past we have solved this problem by creating a 1" graphic of a scale bar and aligning this with a scale text element. This works but limits you to a 1" long scale bar. We would prefere on some maps to have a 2 or 3 inch scale bar. So, can this be done with ESRI software? Thanks.

Mapping Center Answer:

You can do this using a custom script. Here is a link to something similar that you can start with and then modify:

http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=FFBB051B-1422-2418-88A0-9DD853478BA3 (this link provides a script that moves a data frame. It may provide a framework to help write a script that moves the scale bar on and off the page)

This link provides information aboutmap surround elements which a scale bar is: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/MapsurroundElement/00s300000035000000/ 

However, you might want to think about this problem a little differently. There are really two parts to this question. Having a scale bar remain a constant size, and having it remain a useful size. Let's look at it remaining a constant size first.

First, size the scale bar to the dimensions you like then right click the scale bar and open the properties. In the Scale and Units tab there is an option that reads When Resizing… You want to set this to Adjust Division Value. This will keep the scale bar very close to the size you established even when you change scales.

Second, to keep the scale bar a useful size you could try enabling Data Driven Pages. On the Data Driven Pages toolbar click the first button to access the Data Driven Pages Setup. Next click the Extent tab where you will see an option to round the scale called Round Scale to Nearest. You can type in a value here; for example, if you type "1000" the scale will be rounded to the nearest 1000. This functionality will round the scale and the scale bar should show more useable divisions.

If some maps actually have different requirements for the scale bar you could try creating a python script with Arcpy that will move the appropriate scale bar onto the appropriate page. Again this would be a Data Driven Pages solution. You would make a 1 inch scale bar and a 2 inch scale bar. Place the 2 inch scale bar off the page. When printing to PDF the script would ascertain the scale of the map and then swap the scale bars if required. This solution requires some scripting.

Interesting ideas posted by Zorba Conlen on Mar 15 2011 5:08PM
Thanks for the thoughtful reply. This gives me a few options to consider. Cheers.
Happy to help! posted by Aileen Buckley on Mar 16 2011 2:36PM
Glad you found this useful!
Interesting but can someone post the python they u posted by Chandeep Corea on Apr 12 2012 4:20PM
I agree but it would be useful if ESRI or a user could post a script that could be modified by users to fix the issue rather than having to start from scratch. If I am able to fix the issue I will post my script here.
Please do! posted by Aileen Buckley on Apr 13 2012 8:00AM
Please do feel free to get in touch with us if you come up with a script tht can be easily modified by otehrs. We would be happy to help you share it with others.

As a note - the existing sizing options (Scale Bar Properties > Scale and Units tab > When resizing…) give users some control over which aspect of the scale bar gets adjusted when the map scale changes. But they are ALL designed to do some adjusting to ensure scale bar division VALUES are round numbers, depending on map scale.
ArcGIS Ideas posted by Aileen Buckley on Apr 13 2012 10:41AM
P.S. There is an idea on the ideas site, at http://ideas.arcgis.com/ideaView?id=087300000008D7LAAU, asking for fixed scale bar size. If you go there and vote to support this, it will get more attention.

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